It is well known to provide closed circuit television surveillance systems in which video signals generated from a considerable number of video cameras are to be selectively distributed for display among a number of video monitors. In such systems, a video switching apparatus is connected between the cameras and the monitors to perform the signal distribution function.
The number of cameras and the number of monitors which customers desire to include in their surveillance systems are subject to considerable variation. Consequently, it is desirable that the switching apparatus be assembled from modular components, so that the switching capacity of the apparatus, and possibly other features, can be tailored to meet the customer's needs. However, assembly, diagnosis and maintenance of a modular video switching apparatus may present some difficulties. When the apparatus is to be assembled, the factory employee is usually presented with documents such as a configuration table and a bill of materials which are intended to indicate the number and types of components to be incorporated in the apparatus. Such documents refer to the components by designations such as part numbers and/or word descriptions of the components. Often the part numbers convey little or no information about the corresponding component, and the meanings of word descriptions can also be unclear. Moreover, it can be difficult to recognize the components by sight and to correctly match the components with the word or part number designations. As a result, assembling a modular system can be a complex and error-prone task. These problems are exacerbated by the large number of different configurations which may be possible, even when only a fairly small number of distinct components are used.
Other difficulties in identifying and referring to system components may be encountered during trouble-shooting or system maintenance operations For example, it is not unusual for an untrained person at the customer's location to be in telephone communication with a customer service representative. Attempts by the customer service representative to direct the untrained person to manipulate, remove or exchange system components may be seriously encumbered by the untrained person's unfamiliarity with part number and word designations for the system components, and/or inability on the part of the untrained person to match the designation to an actual component in the system. It also may be quite difficult for the customer service representative to provide a physical description of a particular system component in terms which will be understood by the untrained person.
It has been known to provide a video matrix switching device constructed from printed circuit board components contained in dedicated slots in the housing with color-coded designations on the housing to indicate what type of printed circuit board belongs in each slot. Corresponding color code indications were provided on the circuit boards to guide production workers to insert the circuit boards into the correct dedicated slot. However, this arrangement greatly restricted the number of different configurations of switcher that could be produced using a given type of housing.